In Helvetica Chemica Acta Vol. 52, pages 329=333 (1969) and Felder U.S. Pat. No. 3,576,854 there is described the optical splitting of (R) (S)-(1-phenylethyl)-amine, (R) (S)-2-aminobutanol-(1) and 1-(R) (S)-threo-1-(4-nitrophenyl)-2-aminopropanediol-(1,3) using N-[(R)-(1-phenylethyl)]- or N-[(S)-(1-phenylethyl)]-succinic acid monoamide and for splitting of (R) (S)-1-phenyl-2-aminopropane using N-[(R) or (S)-(1-phenylethyl)]-phthalic acid monoamide.
Furthermore it is known to separate racemic norephedrine into the right and left light rotating forms with optically active pantolactone (German Offenlegungsschrift 2,558,507).
However, in the known processes the yields of the pure optically active forms are unsatisfactory; also, frequently the purity of the product of the process is insufficient.